Relations between Russia and Turkey have deteriorated sharply since Turkish F16s brought down a Russian fighter plane along the Syrian border.Ankara says the jet violated Turkish airspace, whereas Moscow insists that Turkey shot down its plane over Syrian territory. The messages, which present very different versions of the facts, have since been amplified in the media of both countries.For both Russian President Vladimir Putin, and Turkey's President Recep Tayyip Erdogan, the Syrian conflict is a geopolitical minefield, which is why both nations are determined to control what is being said over the airwaves.Strong on propaganda, less so on independent journalism, this is a story in which challenging the official line is a risky business.